The present invention relates to torque transmitting and torsion damping apparatus, especially to improvements in torque transmitting and torsion damping apparatus which can be utilized in motor vehicles to compensate for fluctuations of torque which is transmitted between driving and driven components, particularly between the crankshaft of the internal combustion engine and the input shaft of the change-speed transmission in a passenger car or another motor vehicle.
It is already known to provide a torsion damping apparatus, which is installed in a motor vehicle between the crankshaft of the internal combustion engine and the input shaft of the change-speed transmission, with several flywheels which are rotatable relative to each other within certain limits and against the opposition of one or more dampers. Such apparatus are disclosed, for example, in commonly owned copending patent application Ser. No. 669,657 of Oswald Friedmann as well as in several other pending applications of the assignee. The flywheels can rotate relative to each other about the axis or axes of one or more bearings. A friction clutch is interposed between the last flywheel and the input shaft of the transmission, and such friction clutch includes a disc which is movable into and out of friction- and heat-generating engagement with the adjacent flywheel. This can adversely influence the operation and useful life of the bearing, especially if the races of the bearing are directly connected to or in direct contact with the adjacent flywheels. Thus, one race of an antifriction ball bearing between two coaxial flywheels which can move angularly relative to each other against the opposition of one or more dampers can be non-rotatably secured to one of the flywheels, and the other race of the bearing can be non-rotatably secured to the other flywheel. It has been found that the just described mounting of the flywheels on an antifriction bearing enables the damper or dampers to produce a highly satisfactory damping action. Nevertheless, such torsion damping apparatus failed to gain popularity in the automotive and other industries, primarily because the useful life of the bearing or bearings between the flywheels is relatively short. The bearing or bearings are one of the critical elements in these torsion damping apparatus so that their failure after a relatively short interval of use deters the manufacturers of motor vehicles from employing such torsion damping apparatus between the engine and the change-speed transmission.
A torque transmitting and torsion damping apparatus between the input shaft of a change-speed transmission and the output shaft of an engine must be capable of taking up stresses, such as those attributable to fluctuations of transmitted torque, which develop while a rotary driving element transmits torque to a rotary driven element. As a rule, or in many instances, the crankshaft of the engine is attached directly to a first flywheel, the input shaft of the transmission can receive torque from a second flywheel by way of a friction clutch, and the means for transmitting torque between the flywheels comprises one or more dampers which oppose angular movements of the flywheels relative to each other. The second flywheel has a friction surface which is engaged by a lining of the clutch disc of the friction clutch when the latter is engaged to transmit torque from the second flywheel to the transmission. The bearing or bearings between the flywheels has or have pairs of races confining single or multiple rows of antifriction rolling elements in the form of needles, balls, rollers or the like. The bearing or bearings enables or enable the torque transmitting and torsion damping apparatus to perform a highly satisfactory damping of oscillations which develop in the power train between the engine and the transmission. Nevertheless, and as already stated above, such apparatus failed to gain widespread acceptance due to the short useful life of the bearing or bearings. As a rule, the bearing or bearings constitutes or constitute the first part or parts which requires or require replacement, and such replacement must take place after a relatively short period of use.
One of the main reasons that the useful life of the antifriction bearing or bearings between the flywheels of the above outlined torque transmitting apparatus is relatively short is that the bearings are subjected to pronounced thermal stresses, primarily because the friction clutch between the input element of the change-speed transmission and the respective flywheel invariably generates heat when it is called upon to transmit torque to the transmission.
The damper or dampers which are provided between the relatively movable flywheels of the just outlined torque transmitting apparatus normally comprise at least one set of coil springs or analogous energy storing elements which yieldably oppose angular movements of the flywheels relative to each other, as well as one or more friction generating devices each of which can oppose some or all angular movements of the flywheels relative to one another. The damper or dampers contribute significantly to the initial and maintenance cost of the torque transmitting apparatus.
An object of the invention is to provide a torsion damping apparatus which can be used in motor vehicles as a superior substitute for heretofore known torsion damping apparatus and is constructed, dimensioned and assembled in such a way that it and its bearing or bearings can stand long periods of use.
Another object of the invention is to provide a torsion damping apparatus wherein the bearing or bearings between the flywheels can be shielded from undesirable influences of the adjacent parts of the apparatus in a simple and inexpensive but efficient way.
A further object of the invention is to provide a torsion damping apparatus wherein the damper or dampers can perform their functions more efficiently than in heretofore known apparatus, even though their construction need not depart, or need not appreciably depart, from the construction of dampers in conventional torsion damping apparatus.
An additional object of the invention is to provide a novel and improved method of shielding the bearing or bearings and/or the damper or dampers of a torsion damping assembly from undesirable influences of other component parts of the apparatus, especially of the friction clutch between one of the flywheels and the input element of the change-speed transmission in a motor vehicle.
Still another object of the invention is to provide a torsion damping apparatus which exhibits the above outlined features but need not be bulkier, more complex and/or more expensive than heretofore known apparatus.
A further object of the invention is to provide an apparatus which is designed for controlled transmission of torque between the crankshaft of the internal combustion engine and the input shaft of the change-speed transmission in a motor vehicle and is capable of effectively opposing and damping undesirable fluctuations of torque in the power train between the engine and the wheels of the vehicle.
Another object of the invention is to provide a novel and improved method of combining the bearing or bearings with other parts of the above outlined torsion damping apparatus.
Another object of the invention is to provide novel and improved bearings for use in the above outlined torsion damping apparatus.
An additional object of the invention is to provide novel and improved flywheels for use in the above outlined torsion damping apparatus.
A further object of the invention is to provide a novel and improved method of preventing heat from adversely influencing the bearing or bearings and/or other sensitive parts of a torsion damping apparatus of the type wherein a flywheel can transmit torque to a rotary element by way of a friction clutch.
An additional object of the invention is to provide a novel and improved device for preventing heat which is generated during actual use of the torsion damping apparatus from affecting the useful life of certain sensitive parts including the bearing or bearings and one or more dampers.
Another object of the invention is to provide novel and improved means for preventing escape of lubricant from the bearing or bearings in a torsion damping apparatus of the above outlined character.
A further object of the invention is to provide a torsion damping apparatus wherein the useful life of the bearing or bearings can match the useful life of other constituents.
Another object of the invention is to provide the above outlined apparatus with novel and improved means for preventing the heat which is generated by the friction clutch from adversely influencing the bearing or bearings between the flywheels.
A further object of the invention is to provide a relatively simple, compact and inexpensive torque transmitting apparatus which can be used with particular advantage between the crankshaft of the internal combustion engine and the input element of the change-speed transmission in a motor vehicle.
An additional object of the invention is to provide a novel and improved method of shielding the bearing or bearings between the flywheels from excessive thermally induced stresses.
Still another object of the invention is to provide an apparatus of the above outlined character whose components can be assembled or taken apart in a simple and time-saving manner and which can automatically ensure uniform wear upon the component parts of the bearing or bearings between the flywheels.
A further object of the invention is to provide the apparatus with novel and improved means for damping and opposing the movements of flywheels relative to each other.
A further object of the invention is to provide a novel and improved mounting for the bearing or bearings between the flywheels as well as to provide novel and improved damper means between such flywheels.
Another object of the invention is to achieve the above-enumerated objects in a simple and inexpensive way.
Another object of the invention is to provide the apparatus with novel and improved means for prolonging the useful life of the antifriction bearing or bearings between the components of its flywheel.
A further object of the invention is to provide novel and improved means for withdrawing heat and for keeping heat away from the bearing or bearings of the above outlined apparatus.
Still another object of the invention is to provide the torque transmitting apparatus with a simple and inexpensive flywheel and with novel and improved means for cooling one or more parts of the friction clutch between the flywheel and the input shaft of the change-speed transmission.
An additional object of the invention is to provide an apparatus wherein heat is withdrawn from the friction clutch in a direction to avoid the transfer of such heat to sensitive parts of the apparatus.
A further object of the invention is to provide a power train which embodies the above outlined apparatus and to provide a motor vehicle which embodies the power train and the apparatus.
An additional object of the invention is to provide a novel and improved method of cooling the flywheel, the antifriction bearing means and/or the clutch in the above outlined apparatus.
Another object of the invention is to provide a novel distribution of heat barriers in the flywheel or flywheels of the above outlined apparatus.
An additional object of the invention is to provide a torque transmitting apparatus which is constructed and assembled in the above-outlined manner and can be installed in the power trains of existing motor vehicles.
The invention is embodied in a torsion damping apparatus which is especially suited to take up and to compensate for fluctuations of torque which is transmitted from the crankshaft of the internal combustion engine to the rotary input element of the change-speed transmission in a motor vehicle.
One embodiment of the improved torsion damping apparatus comprises a plurality of flywheels including preferably but not necessarily coaxial first and second flywheels which are movable angularly relative to each other, single or plural damper means operating between the first and second flywheels to yieldably oppose angular movements of such flywheels relative to each other, bearing means (e.g., one or more antifriction needle, ball or roller bearings with coaxial inner and outer races) which is interposed between the first and second flywheels and has at least one row of antifriction rolling elements, and a friction clutch which is operable to receive torque from one of the first and second flywheels with attendant generation of heat. The one flywheel and the friction clutch have cooperating first and second friction- and heat-generating surfaces (the first friction generating surface can constitute one side face or end face of the one flywheel, and the second surface can constitute the exposed surface of one friction lining on a clutch disc forming part of the friction clutch and serving to transmit torque to the input element of the change-speed transmission), and the improved torsion damping apparatus further comprises one or more thermal barriers and/or other suitable means for impeding (preferably blocking) the transfer of heat from the first surface to the bearing means.
The impeding means can be installed between the bearing means and the one flywheel. One race of the bearing means can be non-rotatably installed in the one flywheel, and the impeding means (e.g., a thermal barrier) can be mounted between such one race and the one flywheel.
The impeding means can contain or can consist of a synthetic plastic material, a metallic material or a ceramic material. For example, the impeding means can contain a duroplast i.e., a thermosetting resin (e.g., a phenoplast in the form of hard paper). If the impeding means is made of or contains a thermoplastic material, such material can be selected from the group consisting of polytetrafluoroethylene, polyimide and polyamidimide. It is further possible to make the thermal barrier of a material which contains a polycarbonate, especially a fiber-reinforced polycarbonate.
The first flywheel can be formed with a central protuberance and the second flywheel is then provided with a centrally located recess which receives at least a portion of the protuberance as well as a portion of or the entire bearing means which then surrounds a portion of or the entire protuberance. The impeding means is or can be mounted in the recess and at least partially surrounds or is surrounded by the bearing means, depending upon whether the recess is provided in the one flywheel or in the other of the first and second flywheels. For example, one race of the bearing means can be arranged to rotate with the one flywheel, and the impeding means can be interposed between such race and the one flywheel so that it rotates with the one flywheel. The other race of the bearing means then surrounds the protuberance of the other of the first and second flywheels. The impeding means can be integral with the bearing means; for example, such impeding means can comprise a thermal barrier which is bonded to the bearing means in an extruding or injecting  injection molding machine. Also, if the thermal barrier contains sintered material, such material can be integral with the bearing means. Alternatively, the thermal barrier can be a press fit on or in the bearing means. it  It is also possible to assemble the bearing means and the first flywheel into a prefabricated unit which fits, with a certain annular clearance, into a centrally located recess of the second flywheel and such clearance is filled with a mass of plastic material which is allowed to set and can constitute or form part of the impeding means. The hardened plastic material then surrounds the outer race of the bearing means and can be inserted into the centrally located recess of the one flywheel, i.e., of that flywheel which can transmit torque to the input element of the change-speed transmission in response to engagement of the friction clutch.
The impeding means can include or constitute a means for sealingly engaging (e.g., surrounding) at least a portion of the bearing means.
The impeding means can comprise a ring-shaped thermal barrier including a substantially cylindrical section which overlaps the first race of the bearing means, and at least one radially disposed section which extends from the cylindrical section toward the other race of the bearing means. One of the races surrounds the other race, and the cylindrical section can surround the outer of the two races. The ring-shaped thermal barrier can have a substantially L-shaped cross-sectional outline, and the radially extending section of such thermal barrier can include an annular portion (e.g., an annular marginal portion) which bears against the other race of the bearing means, as considered in the axial direction of the flywheels. The impeding means can comprise two mirror symmetrical rings each of which has an L-shaped cross-sectional outline and whose cylindrical sections surround the outer race of the bearing means. The radial sections of such rings extend from the respective cylindrical sections along the corresponding end faces of the two races, and each radial section thereof can extend across the corresponding end of the annular clearance between the inner and outer races of the bearing means. Thus, the outer race of the bearing means is then disposed between the radial sections of the two rings which constitute or form part of the impeding means. The two rings are mirror symmetrical to each other with reference to a plane which is disposed between them and is normal to the common axis of the flywheels.
Each radial section can be biased axially of the flywheels and against the respective end face of the inner race by a diaphragm spring or by other suitable biasing means. The outer marginal portion of each diaphragm spring can react against the one flywheel, and the inner marginal portion of each diaphragm spring then bears against the radial section of the respective ring. Such inner marginal portions can cause the aforediscussed annular lips (if any) of the radial sections to bear against the respective end faces of the inner race.
A sleeve-like section of a thermal barrier which constitutes or forms part of the impeding means can be a press fit in the centrally located recess of the first or second flywheel. The sleeve-like section and the bearing means can constitute a prefabricated unit which is received in the recess. The sleeve-like section of the thermal barrier can surround the outer race of the bearing means and its thickness, as considered radially of the flywheels, can vary in the axial direction of the bearing means. At least the thicker portion of the sleeve-like section can be a press fit in the recess of the first or second flywheel.
The ring or rings of the thermal barrier can define with one of the races one or more annular chambers for suitable sealing means, such as one or more O-rings. For example, if the thermal barrier comprises a single ring having a substantially L-shaped cross-sectional outline, the cylindrical section of the ring can surround the external surface of the outer race of the bearing means, the radial section of the ring can extend from the cylindrical section inwardly along one end face of the outer race and along the corresponding end face of the inner race, and the annular chamber can be provided at the junction of the two sections, i.e., in the region where the one end face of the outer race meets the peripheral surface of the outer race. The chamber can be formed by providing the outer race of the bearing means with an annular groove. The sealing means (such as the aforementioned O-ring) can be received in the chamber and can be compressed therein by a shoulder of the outer race of the bearing means.
The thermal barrier can comprise a ring-shaped section having a frustoconical external and/or internal surface in contact with a complementary surface of the one flywheel and/or the outer race of the bearing means. Means (such as the aforementioned diaphragm spring) can be provided to bias the ring-shaped section of the thermal barrier axially in the direction of the taper of the ring-shaped section, i.e., so that the larger-diameter end of the frustoconical internal surface or the smaller-diameter end of the frustoconical external surface is the leading end of the ring-shaped section. Such section can constitute a split ring, or it can be assembled of two or more discrete arcuate sections. If the thermal barrier further comprises at least one sealing element, the latter extends radially of the ring-shaped section and toward that race of the bearing means which is not in contact with the cylindrical part of the ring. A diaphragm spring or other means can be provided to bias the sealing element axially against that race which is not engaged by the cylindrical part of the ring, for example, to bias an annular lip of the sealing element against the adjacent race of the bearing means. The ring can include a radial section which is disposed opposite the sealing element and can constitute an integral part of the cylindrical section. The radial section and the sealing element then flank the two races of the bearing means.
The means for impeding the transfer of heat to the bearing means can perform the function of or cooperates with the aforementioned damper means which yieldably opposes angular movements of the flywheels relative to each other. The clutch preferably comprises a clutch disc, and the first surface of the one flywheel is adjacent the clutch disc. The clutch also comprises means (e.g., a diaphragm spring) for biasing the first surface of the one flywheel and the clutch disc into frictional engagement with each other when the clutch is engaged whereby the clutch causes the generation of heat which is transmitted to the one flywheel. The opposing means may but need not constitute the only means which tends to resist angular movements of the flywheels relative to each other.
The bearing means can comprise an antifriction needle, ball or roller bearing having a race for the rolling elements. The race is adjacent and preferably rotates with the one flywheel, and the opposing means preferably includes a first portion (e.g., the annular portions of two mirror symmetrical rings each of which has a substantially L-shaped cross-sectional outline) which is interposed between the race and the one flywheel, and a second portion (e.g., the radially extending portions of the aforementioned rings) which is in direct or indirect frictional engagement with the other flywheel. The antifriction bearing preferably further comprises a second race which is connected to and shares the angular movements of the other flywheel. The second portion of the opposing means is or can be in direct frictional engagement with the second race. As mentioned above, the second portion of the opposing means can extend substantially radially of the flywheels and of the antifriction bearing, and the first portion of such opposing means preferably extends circumferentially of the race which rotates with the one flywheel. The radially extending portions of the rings preferably abut, or are at least adjacent, the end faces of the second race, i.e., of that race which shares the angular movements of the other flywheel.
The opposing means can further comprise one or more dished springs or analogous energy storing means for at least indirectly biasing the second portions of the rings against the other flywheel, e.g., by biasing such second portions axially of the flywheels against the end faces of the race which rotates with the other flywheel. A first portion of each dished spring can react against the one flywheel, and a second portion of each dished spring (such second portions are preferably disposed radially inwardly of the respective first portions) bears against the second portion of the corresponding ring. The distance between the second portions of the dished springs and the axes (e.g., the common axis) of the flywheels preferably equals or approximates the distance between such axes and those parts of the second portions of the rings which bear against the end faces of the second race and/or directly against the other flywheel.
The bias of one of the dished springs can exceed the bias of the other dished spring so that the rolling elements of the bearing means are clamped between the two races when the clutch is disengaged in that the second race tends to move axially with reference to the race which rotates with the one flywheel. The force which is required to disengage the clutch and acts axially of the flywheels is opposed by the one dished spring i.e., the force of the one dished spring must be overcome in order to disengage the clutch. The second portions of the rings can further serve as a means for at least substantially sealing the axial ends of the annular space which is defined by the two races of the bearing means and receives the rolling elements.
A further feature of the invention resides in the provision of an apparatus wherein the friction clutch has a clutch plate having the aforementioned second surface which is engageable with the (first) surface of the one flywheel. The damping means of such apparatus can comprise two series-connected damping units and one or more friction generating units which are interposed between the flywheels to yieldably oppose rotation of the flywheels relative to each other. The first surface and the bearing means are preferably spaced apart from each other in the radial direction of the flywheels, and the impeding means of such apparatus includes a portion of the one flywheel; to this end, the one flywheel is provided with substantially axially extending passages which are disposed intermediate the bearing means and the first surface, i.e., radially outwardly of the bearing means.
At least one passage is or can be elongated, e.g., at least one passage can constitute a slot and the passages preferably form an annulus which surrounds the bearing means.
In accordance with a presently preferred embodiment of this apparatus, each passage has a slot-shaped end portion in the first surface, and the cross-sectional area of at least one passage increases in a direction away from the first surface (preferably close to or all the way to an additional surface of the one flywheel opposite the first surface). The arrangement may be such that the internal surfaces which bound some or all of the passages resemble the surfaces surrounding fluid-circulating vanes or blades.
The passages are or can be adjacent (particularly closely adjacent) the bearing means (the latter can include one or more radial and/or axial antifriction bearings with a pair of races and needle-, roller- or ball-shaped rolling elements between the races).
Those end portions of the passages which are provided in the additional surface of the one flywheel preferably extend substantially radially outwardly away from the bearing means. The just discussed end portions of the passages can extend at least close to or all the way to and even beyond the radially outermost portion of the first surface.
The internal surfaces which bound the passages can include inner portions which are nearer to the axes of the flywheels and extend in substantial parallelism with such axes all the way between the first and additional surfaces of the one flywheel, and outer portions which are more distant from the axes of the flywheels and extend in a direction from the first surface and radially of and away from the axes of the flywheels.
The passages are, or can be, equidistant from each other in the circumferential direction of the one flywheel, and they preferably form an annulus with its center on the axes of the flywheels. The combined length of the passages (as measured in the circumferential direction of the one flywheel) can be between 20 and 70 percent of the corresponding portion of the one flywheel. The one flywheel comprises webs which alternate with the passages of the aforementioned annulus, and the width of each such web (measured in the circumferential direction of the one flywheel) can be between 0.5 and 2.5 times the width of a passage. The webs can be said to constitute, or they can be designed to constitute, heat barriers between the passages. Such heat barriers are integral portions of the one flywheel, and they cooperate with the streams of air flowing through the passages when the one flywheel rotates to prevent an overheating of the bearing means.
The damping means can comprise an annulus of rivets or analogous fasteners which are fixed to the one flywheel and alternate with the passages (as considered in the circumferential direction of the one flywheel). The fasteners can be used to attach a disc- or flange-like output member of the damping means to the one flywheel. The diameter of the annulus which is formed by the passages can closely approximate or equal the diameter of the annulus of fasteners. Such fasteners extend through at least some of the aforementioned web-like heat barriers of the one flywheel. The fasteners can alternate with pairs of passages (as considered in the circumferential direction of the one flywheel). The webs can include wider webs and narrower webs, and the fasteners are preferably secured to the wider webs. The width of each wider web can equal or approximate the combined width of the two narrower webs.
The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.